Large-scale deployment of 3G networks greatly drives use of data services. Quick development of OTT (Over The Top, Internet service) services makes operators gradually channelized. To improve accurate charging and control for network traffic of operators, improve user experience, and increase the value of unit traffic, charging and control for an OTT application has become an important technical means.
PCC (Policy and Charging Control, policy and charging control) is a policy and charging control mechanism defined by the 3GPP (3rd Generation Partnership Project, 3rd Generation Partnership Project), and an architecture of PCC is shown in FIG. 1. The architecture includes a policy and charging enforcement function (PCEF device, Policy and Charging Enforcement Function), a traffic detection function (TDF, Traffic Detection Function), a bearer binding and event reporting function (BBERF, Bearer Binding and Event Reporting Function), a policy and charging rules function (PCRF device, Policy and Charging Rules Function), an application function (AF, Application Function), an online charging system (OCS, Online Charging System), an offline charging system (OFCS, Offline Charging System), and a subscription profile repository (SPR, Subscription Profile Repository). The architecture includes interfaces such as Gx, Sy, Gy, and Ro interfaces, where the Gx is an interface between the PCRF and the PCEF, the Sy is an interface between the PCRF and the OCS, the Gy is an interface between the PCEF and the OCS, and the Ro is a collective name of online charging interfaces between network elements and the OCS. The PCEF device is a policy and charging enforcement entity and is used to execute a dynamic or static control policy and may be located in a gateway device such as a GGSN and a P-GW or placed behind a gateway device. The TDF is an application detection and control entity and is used to execute an application detection and control policy delivered by the PCRF device. The PCRF device is a policy and charging rules function entity in charge of controlling the QoS, bandwidth, gating, a charging policy, and so on when a user equipment uses a service in a home network. The SPR is a subscription data storage entity, and is used to store subscription data of a user and map the data to an existing system. The SPR may be an HLR, an HSS, an OCS, or other entities. In the mechanism, the PCRF entity performs policy generation (Policy Decision) to generate a data flow charging and control policy for the PCEF entity and an application detection and application control policy for the TDF entity. Then the PCRF entity installs and activates an application control policy for the TDF entity and installs a flow control and charging policy for the PCEF entity. According to a data flow charging policy delivered by the PCRF entity, the PCEF entity initiates a data flow credit quota request, namely, a credit control request (Credit Control Request, CCR) message, to the OCS (where if a bearer is to be established, the PCEF entity initiates a charging session establishment request to the OCS). The OCS grants the quota and returns the granted quota to the PCEF entity.
In this mechanism, a charging policy delivered by the PCRF to the PCEF includes charging rule parameters of a service data flow (SDF, Service Data Flow), specifically including: online or offline charging, rating group (Rating Group), report level (Report Level), traffic-, duration- or event-based charging, and so on.
When executing a charging policy delivered by the PCRF, the PCEF establishes a charging session with the OCS. The specific manner of establishing a charging session is as follows:
For a general packet radio service (General Packet Radio Service, GPRS), the PCEF establishes a charging session for each Packet Data Protocol (Packet Data Protocol, PDP) context (PDP Context). The PCEF establishes a charging session when a PDP Context starts, and terminates the charging session when the PDP Context ends or when the OCS initiates session termination.
For an evolved packet core (Evolved Packet Core, EPC), if an S5 interface is based on the GPRS Tunneling Protocol (GPRS tunneling protocol, GTP), the PCEF establishes a charging session for each IP connectivity access network bearer (IP-CAN Bearer). The PCEF establishes a charging session when an IP-CAN Bearer starts, and terminates the charging session when the IP-CAN bearer ends or when the OCS initiates session termination.
For the EPC, if the S5 interface is based on the Proxy Mobile IP Protocol (Proxy Mobile IP Protocol, PMIP), the PCEF establishes a charging session for an IP connectivity access network session (IP-CAN Session). The charging session is regarded as a charging session on an IP-CAN Bearer and transmits a parameter of the IP-CAN Bearer.
The existing charging is based on the IP-CAN Bearer. The parameter (carried in a PS-information parameter) of the IP-CAN Bearer is reported to the OCS. In addition, charging information collected with a rating group or rating group+service ID as a granularity is reported.
Based on the existing charging mechanism, a prerequisite for charging for an application is that the PCRF knows the flow description of the application, namely, an IP quintuple, and that flows of the application are on a same bearer. The PCRF delivers a charging policy of the application flow on a bearer to the PCEF, and the PCEF performs IP layer parsing on an IP packet, that is, packet parsing of L3/4 layer according to service data flow (SDF, Service Data Flow) information in the charging policy, and further collects charging information about the application flow on a unified basis and reports the information to a charging system under certain conditions, so as to implement charging for the application. In this charging mode, because the PCRF knows the IP quintuple attribute of an application packet in advance and binds the application flow to a bearer, charging for the application can be implemented in an existing charging mode based on an IP-CAN Bearer.
The following technical problems exist during implementation of the existing technical solution:
1) It is difficult to ensure that a flow of an application is transmitted on one bearer, so that an existing charging session based on a granularity of a bearer can transmit only charging information about this bearer and the requirement for application-based charging for a cross-bearer OTT application cannot be met.
2) When the TDF detects an application, if a feature of the application flow cannot be described using a quintuple or the quintuple attribute of the application flow changes frequently, which causes the PCRF and the PCEF to make change frequently and results in low system availability, it is difficult to implement charging for an OTT application.